Broadcom ACPL-C740 Sigma-Delta Modulators

Broadcom ACPL-C740 Sigma-Delta Modulators convert an analog input signal into a high-speed data stream with galvanic isolation based on optical coupling technology. The ACPL-C740 operates from a 5V power supply with a dynamic range of 83dB with a designated digital filter. The differential inputs of ±200mV (full-scale ±320mV) are ideal for direct connection to shunt resistors. The inputs are also utilized in other low-level signal sources in applications. The ACPL-C740 has an analog input that is continuously sampled by a means of sigma-delta over-sampling using an onboard clock. The signal information is contained in the modulator data as a density of ones with a data rate of 20MHz. This data is then encoded and transmitted across the isolation boundary, where they are recovered and decoded into a high-speed data stream of digital ones and zeros.

The original signal information can be reconstructed with a digital filter. The serial interface for data and clock has A wide supply range of 3V to 5.5V is offered in the serial interface for data and clock. The modulator, combined with superior optical-coupling technology, delivers high noise margins and excellent immunity against isolation-mode transients. The ACPL-C740 provides reliable reinforced insulation and high working insulation voltage with a 0.5mm minimum distance through insulation (DTI), making it suitable for fail-safe designs. The isolated ADC delivers the reliability, small size, superior isolation, and over-temperature performance that motor drive designers need to measure current accurately.


  • Superior optical isolation and insulation
  • 20MHz internal clock
  • 1bit, second-order sigma-delta modulator
  • 16bits resolution no missing codes (12bits ENOB)
  • 83dB SNR
  • 2μV/°C maximum offset drift
  • 3V to 5.5V wide supply range for digital interface
  • ±1% gain error
  • Internal reference voltage
  • ±200mV linear range with single 5V supply (±320mV full scale)
  • –40°C to +110°C operating temperature range
  • SSO-8 package
  • 25kV/μs common-mode transient immunity
  • Safety and regulatory approval:
    • IEC/EN/DIN EN 60747-5-5: 1414 Vpeak working insulation voltage
    • UL 1577: 5000 Vrms/1min isolation voltage
    • CSA: Component Acceptance Notice #5


  • Servo drives and motors
  • Motor phase and rail current sensing
  • Power inverter current sensing
  • Industrial process control
  • Data acquisition systems
  • General purpose current sensing
  • Traditional current transducer replacements

Block Diagram

Block Diagram - Broadcom ACPL-C740 Sigma-Delta Modulators
Publicado: 2018-12-17 | Actualizado: 2022-07-28